The invention relates to an apparatus for severing blanks, especially collar blanks of a hinge lid pack, from a web of material, which apparatus comprises severing knives (knife edges), which are arranged on a rotating knife roller, and a counter means, preferably a counter roller which also rotates, the knife roller resting against the web of material or the counter means with a resilient pressure resulting from spring means.
Packaging machines are often equipped with cutting or punching tools which produce the blanks which are processed in the packaging machine by way of severing the blanks from a web of material. The cutting tools are subjected to considerable wear and tear, especially if the blanks which are to be produced are made of thin cardboard and the packaging machine has a particularly high capacity.
Hinge lid packs for cigarettes etc. normally have a collar which is formed from a separate blank (U.S. Pat. No. 4,084,393). The collar is severed from a web of cardboard within the packaging machine (U.S. Pat. No. 4,938,005).
The cutting and severing tools employed for this purpose consist of a rotating knife roller. Cutting knives which are in the form of projecting knife edges are arranged on the shell surface of the knife roller in such a way that a they correspond to the contours of the (collar) blanks. A counter roller which also rotates and which has a smooth cylindrical shell surface serves as a counter pressure means. The web of material is conveyed through between knife roller and counter roller.
To apply precise severing cuts, it is important that the contact pressure of the knife roller and therewith the cutting pressure is adjusted as accurately as possible. This pressure must remain as accurate as possible even when the knife edges start to wear.